New methods for Frequency Signal Modelling and Impact Evaluation of New Resources

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Hyperthyroidism and cardiovascular complications: a narrative review on the basis of pathophysiology

Cardiovascular complications are important in hyperthyroidism because of their high frequency in clinical presentation and increased mortality and morbidity risk. The cause of hyperthyroidism, factors related to the patient, and the genetic basis for complications are associated with risk and the basic underlying mechanisms are important for treatment and management of the disease. Besides cellular effects, hyperthyroidism also causes hemodynamic changes, such as increased preload and contractility and decreased systemic vascular resistance causes increased cardiac output. Besides tachyarrythmias, impaired systolic ventricular dysfunction and diastolic dysfunction may cause thyrotoxic cardiomyopathy in a small percentage of the patients, as another high mortality complication. Although the medical literature has some conflicting data about benefits of treatment of subclinical hyperthyroidism, even high-normal thyroid function may cause cardiovascular problems and it should be treated. This review summarizes the cardiovascular consequences of hyperthyroidism with underlying mechanisms

A framework for second-order eigenvector centralities and clustering coefficients

We propose and analyse a general tensor-based framework for incorporating second-order features into network measures. This approach allows us to combine traditional pairwise links with information that records whether triples of nodes are involved in wedges or triangles. Our treatment covers classical spectral methods and recently proposed cases from the literature, but we also identify many interesting extensions. In particular, we define a mutually reinforcing (spectral) version of the classical clustering coefficient. The underlying object of study is a constrained nonlinear eigenvalue problem associated with a cubic tensor. Using recent results from nonlinear Perron–Frobenius theory, we establish existence and uniqueness under appropriate conditions, and show that the new spectral measures can be computed efficiently with a nonlinear power method. To illustrate the added value of the new formulation, we analyse the measures on a class of synthetic networks. We also give computational results on centrality and link prediction for real-world networks

The relationship between calcium metabolism, insulin-like growth factor-1 and pulse pressure in normotensive, normolipidaemic and non-diabetic patients

Introduction: Recent evidence suggests an interaction between bone metabolism and blood pressure (BP) regulation. The aim of our study was to evaluate endocrinological and metabolic factors related to pulse pressure (PP) in normotensive, normolipidaemic, non-smoker subjects. Material and methods: We consecutively enrolled 156 adults (37 males, 119 females) in summer 2009. The BP and body mass index (BMI) were recorded, and serum samples were taken for 25-hydroxy vitamin D (25-OHD), insulin-like growth factor-1 (IGF-1), growth hormone (GH), parathormone (PTH), calcium, albumin, phosphorus, glucose, triglyceride and cholesterol levels. Results: In the postmenopausal group, PP was significantly associated with age and BMI, while in premenopausal patients it was inversely related to ionized calcium. In men, a reverse relationship was present between GH and IGE-1 levels and PP. Conclusions: The PP was predicted by different parameters in different genders and these predictors change even in the same gender before and after menopause. Well-known predictors of PP such as age and BMI were more pronounced in postmenopausal women, but none of the groups showed a relationship between PP and 25-OHD or PTH

Frequency Models and Control in Normal Operation: the Sardinia Case Study

Frequency signal is an indicator of the unbalance between the power generation and the load demand. Frequency power reserves in different timeframes are commonly deployed to keep this signal inside strict ranges around the nominal value. Reserves must be carefully dimensioned, and their dynamic performance correctly evaluated to enhance system security. This paper proposes a novel methodology to reproduce frequency fluctuations of entire days and to compute the power reserves activation dynamics by using a two-step process. Firstly, given a real power system frequency signal, a reverse aggregate model provides the unbalance in the system. Secondly, this unbalance is used to recreate and validate the original frequency signal by a forward aggregate model. After this procedure, Battery Energy Storage Systems (BESSs) are added and their impact on the frequency signal is quantified, in terms of different control schemes. The proposed method is tested in the real case of the Sardinian power system. Results show that this methodology can provide accurate estimation of the unbalance, frequency and reserves in the system, giving an understanding of the BESS impact on the frequency control

Rheological behavior and morphology of poly(lactic acid)/low‐density polyethylene blends based on virgin and recycled polymers: Compatibilization with natural surfactants

Blends based on poly(lactic acid) and low-density polyethylene were compatibilized exploiting an innovative strategy involving the introduction of different mixtures of two sustainable liquid surfactants characterized by dissimilar hydrophilic–lipophilic ratios. The compatibilization method was first applied on blends made of virgin polymers, aiming at assessing the surfactant mixture inducing a more significant morphology refinement. Besides, to verify the effectiveness of the selected compatibilizers on recycled materials, the same process was carried out on blends based on reprocessed polymers. Interestingly, the compatibilization caused a significant microstructure modification, with a decrease of 54% of the mean size of the dispersed particles, in the case of virgin polymers-based blends, with a consequent increase of 19% of the dynamic elastic modulus. On the other hand, in the case of reprocessed polymers-based blends, a different compatibilizer efficiency was observed, as the noncompatibilized blend showed amore regular microstructure compared to the compatibilized counterpart

Multi-dimensional, multilayer, nonlinear and dynamic HITS

We introduce a ranking model for temporal multidimensional weighted and directed networks based on the Perron eigenvector of a multi-homogeneous order-preserving map. The model extends to the temporal multilayer setting the HITS algorithm and defines five centrality vectors: two for the nodes, two for the layers, and one for the temporal stamps. Nonlinearity is introduced in the standard HITS model in order to guarantee existence and uniqueness of these centrality vectors for any network, without any requirement on its connectivity structure. We introduce a globally convergent power iteration like algorithm for the computation of the centrality vectors. Numerical experiments on real-world networks are performed in order to assess the effectiveness of the proposed model and showcase the performance of the accompanying algorithm

Multi-dimensional, multilayer, nonlinear and dynamic HITS

We introduce a ranking model for temporal multidimensional weighted and directed networks based on the Perron eigenvector of a multi-homogeneous order-preserving map. The model extends to the temporal multilayer setting the HITS algorithm and defines five centrality vectors: two for the nodes, two for the layers, and one for the temporal stamps. Nonlinearity is introduced in the standard HITS model in order to guarantee existence and uniqueness of these centrality vectors for any network, without any requirement on its connectivity structure. We introduce a globally convergent power iteration like algorithm for the computation of the centrality vectors. Numerical experiments on real-world networks are performed in order to assess the effectiveness of the proposed model and showcase the performance of the accompanying algorithm

Bionanocomposite blown films: insights on the theological and mechanical behavior

In this work, bionanocomposites based on two different types of biopolymers belonging to the MaterBi® family and containing two kinds of modified nanoclays were compounded in a twin-screw extruder and then subjected to a film blowing process, aiming at obtaining sustainable films potentially suitable for packaging applications. The preliminary characterization of the extruded bionanocomposites allowed establishing some correlations between the obtained morphology and the material rheological and mechanical behavior. More specifically, the morphological analysis showed that, regardless of the type of biopolymeric matrix, a homogeneous nanofiller dispersion was achieved; furthermore, the established biopolymer/nanofiller interactions caused a restrain of the dynamics of the biopolymer chains, thus inducing a significant modification of the material rheological response, which involves the appearance of an apparent yield stress and the amplification of the elastic feature of the viscoelastic behavior. Besides, the rheological characterization under non-isothermal elongational flow revealed a marginal effect of the embedded nanofillers on the biopolymers behavior, thus indicating their suitability for film blowing processing. Additionally, the processing behavior of the bionanocomposites was evaluated and compared to that of similar systems based on a low-density polyethylene matrix: this way, it was possible to identify the most suitable materials for film blowing operations. Finally, the assessment of the mechanical properties of the produced blown films documented the potential exploitation of the selected materials for packaging applications, also at an industrial level